wifi: rtw88: Stop high queue during scan

When traversing channel list, TX in high queue should be disabled
along with beacon function, so packets won't be sent to incorrect
channels.

Signed-off-by: Po-Hao Huang <phhuang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230616125540.36877-5-pkshih@realtek.com